Contact Cleaning Units in Cmp Polisher

Embodiments of the present invention generally relate to electronic device manufacturing, and in particular, to chemical mechanical polishing (CMP) systems and methods used in a semiconductor device manufacturing processes.

The transfer and air time of a substrate within a chemical mechanical polishing (CMP) system can affect the quality of the substrate. Transfer time, denoting the duration required to relocate the substrate from one station to another in the CMP system, encompasses movements such as transferring the substrate from a carrier to a polishing pad, from the polishing pad to a rinse station, and from the rinse station to a subsequent station in the process. Concurrently, air time refers to the interval during which the substrate is exposed to air between stations in the CMP system, encompassing both travel time between stations and the duration the substrate awaits processing at the subsequent station.

Both transfer time and air time contribute to potential substrate contamination. Exposure to air provides an opportunity for the substrate to accumulate dust particles and other contaminants, subsequently transferring them to the polishing pad and resulting in scratches or other defects on the substrate surface. Further, these temporal factors can impact the uniformity of the CMP process. In instances where the substrate is not quickly transferred between stations, slurry may dry on the substrate surface, leading to uneven material removal and compromising substrate uniformity.

Additionally, extended air exposure can cause surface oxidation, contributing to increased subsurface damage that weakens the substrate, making it more prone to breakage.

Accordingly, there is a need for an improved method and apparatus that reduces substrate transfer and air time in CMP systems.

Embodiments of the present invention generally relate to electronic device manufacturing, and in particular, to chemical mechanical polishing (CMP) systems and methods used in a semiconductor device manufacturing processes. More particularly, embodiments herein provide for processes and methods for reducing substrate transfer and air time in CMP systems.

In an embodiment, a system for polishing a substrate is provided. The system includes one or more polishing stations disposed within a polishing module, a contact cleaning unit disposed adjacent to the one or more polishing stations, and a controller configured to transfer the substrate to a first polishing station of the one or more polishing stations, transfer the substrate to the contact cleaning unit from the first polishing station, and clean the substrate using a contact cleaning method.

In another embodiment, a system for polishing a substrate is provided. The system includes one or more polishing stations disposed within a polishing module in a circular arrangement, a contact cleaning unit disposed adjacent to the one or more polishing stations, and a controller configured to transfer the substrate to a first polishing station of the one or more polishing stations, transfer the substrate to the contact cleaning unit from the first polishing station, and clean the substrate using a contact cleaning method.

In yet another embodiment, a method for polishing a substrate is provided. The method includes placing a substrate on a first non-contact cleaning unit cleaning the substrate using a first non-contact cleaning method, transferring the substrate to a first polishing station, transferring the substrate to a contact cleaning unit from the first polishing station, and cleaning the substrate using a contact cleaning method.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

Embodiments herein generally relate to chemical mechanical polishing (CMP) systems, and in particular, to cleaning systems used with CMP systems and methods related thereto.

The transfer and air time of a substrate in a chemical mechanical polishing (CMP) system significantly affect the quality of the substrate. Transfer time involves moving the substrate between different stations in the CMP system, while air time refers to the duration the substrate is exposed to air during these movements. Both transfer time and air time contribute to potential substrate contamination, as extended exposure to air can lead to the accumulation of dust particles and contaminants on the substrate surface, causing defects. These factors also impact the uniformity of the CMP process, with slow transfers potentially resulting in slurry drying on the substrate surface, leading to uneven material removal and reduced substrate uniformity. Prolonged transfer and air times can result in surface oxidation and heightened subsurface damage, ultimately weakening the substrate and increasing the risk of breakage.

The present disclosure provides for improved systems and methods that incorporate contact clean modules within a polishing module rather than in a post-CMP cleaning module. These contact clean modules reduce substrate transfer time and defectivity between polishing processes within the CMP system.

illustrates a schematic top view of a chemical mechanical polishing (CMP) systemA. The CMP systemA generally includes a factory interface module, an input module, a polishing module, and a cleaning module. These four major components are generally disposed within the CMP systemA.

The factory interface moduleincludes a support to hold a plurality of cassettes, a housingthat encloses a chamber, and one or more interface robots. The interface robotgenerally provides the range of motion required to transfer substrates between the cassettesand one or more of the other modules of the CMP systemA.

Unprocessed substrates are generally transferred from the cassettesto the input moduleby the interface robot. The input modulegenerally facilitates transfer of a substrate between the interface robotand a transfer robot. The transfer robottransfers the substrate between the input moduleand the polishing module.

The polishing modulegenerally includes a transfer station, one or more polishing stations, one or more non-contact cleaning units, and one or more contact cleaning units. The transfer stationis disposed within the polishing moduleand is configured to accept the substrate from the transfer robot. The transfer stationtransfers the substrate to at least one carrier headof a polishing stationthat retains the substrate during polishing.

The polishing stationseach includes a rotatable disk-shaped platen on which a polishing padis situated. The platen is operable to rotate about an axis. The polishing padcan be a two-layer polishing pad with an outer polishing layer and a softer backing layer. The polishing stationseach further includes a dispensing arm, to dispense a polishing liquid, e.g., an abrasive slurry, onto the polishing pad. In the abrasive slurry, the abrasive particles can be silicon oxide, but some polishing processes use cerium oxide abrasive particles. Each polishing stationcan also include a conditioner headto maintain the polishing padat a consistent surface roughness.

The polishing stationseach includes at least one carrier head. The at least one carrier headis operable to hold a substrate against the polishing padduring a polishing operation. Following the polishing operation performed on a substrate, the at least one carrier headtransfers the substrate back to the transfer station.

The transfer robotthen removes the substrate from the polishing modulethrough an opening connecting the polishing modulewith the remainder of the CMP systemA. The transfer robotremoves the substrate in a horizontal orientation from the polishing moduleand transfers the substrate to the cleaning module.

The non-contact cleaning unitmay employ methods like megasonic cleaning or spray cleaning to eliminate particles and contaminants from the substrate surface. For example, the non-contact cleaning unitmay include megasonic cleaning, which utilizes high-frequency sound waves to create cavitation bubbles in the cleaning solution. The implosion of these bubbles generates shock waves that dislodge particles and contaminants from the substrate surface. Alternatively, the non-contact cleaning unitmay include spray cleaning, where high-pressure jets of cleaning solution are used to dislodge particles and contaminants. The non-contact cleaning unitmay be a single-arm spray cleaning module, employing a single spray arm moving back and forth across the substrate or a dual-arm spray cleaning module with two spray arms moving in opposite directions. Further, the non-contact cleaning unitmay be a rotating spray cleaning module that features a rotating spray head above the substrate, spraying cleaning solution from all angles. Additionally, the non-contact cleaning unitmay be an inline spray cleaning module integrated into the CMP process line, transporting the substrate on a conveyor belt and spraying it from multiple angles. Conversely, an off-line spray cleaning module operates independently, cleaning substrates outside the CMP process line, which may be loaded manually or with the transfer robot.

The contact cleaning unit, described further below regarding, directly contacts the substrate and may be a brush scrubbing module using a rotating brush to scrub the substrate surface. The brush moves back and forth across the substrate, applying cleaning solution during the scrubbing process. The rotating brush uses friction between the brush bristles and the substrate surface, as well as centrifugal force generated by the rotating brush to dislodge particles and contaminants from the substrate surface. The cleaning solution concurrently dissolves and weakens the bonds between particles and the substrate surface. Following dislodgment of contaminants from the substrate surface, the cleaning solution, flowing through the brush bristles, flushes the contaminants from the substrate surface.

The non-contact cleaning unitsand the contact cleaning unitsare disposed between the polishing stationssuch that the contact cleaning unitsare in the pass-through between adjacent polishing stations. The non-contact cleaning unitsare adjacent to the at least one carrier headof each of the polishing stations, such that the substrate undergoes a non-contact cleaning immediately before being polished in the. Having the contact cleaning unitsin the pass-through between polishing stationsminimizes polishing-station-to-brush-clean transfer time, reducing defects in the substrate, and reducing the need for additional contact cleaning units in the cleaning moduleresulting in a reduced overall footprint of the entire tool. Alternatively, the CMP systemA may only have the contact cleaning units.

The cleaning modulegenerally includes one or more cleaning devices that can operate independently or in concert. For example, the cleaning modulecan include, from top to bottom in, a sulfuric peroxide mixture (SPM) module, an input module, one or more brush or buffing pad cleaners,, a megasonic cleaner, and a drying module. Other possible cleaning devices include chemical spin cleaners and jet spray cleaners (not shown). A transport system, e.g., an overhead conveyorthat supports robot arms, can walk or run the substrate from cleaning device to cleaning device. Additionally, overhead transfer robots can be used for this same transport of substrates. Briefly, the one or more brush or buffing pad cleaners,are devices in which the substrate can be placed and the surfaces of the substrate are contacted with rotating brushes or spinning buffing pads to remove any remaining particulates. The substrate is then transferred to the megasonic cleanerin which high frequency vibrations produce controlled cavitation in a cleaning liquid to clean the substrate. Alternatively, the megasonic cleanercan be positioned before the brush or buffing pad cleaners,. A final rinse can be performed in a rinsing module before being transferred to the drying module.

The CMP systemA includes a controller, which generally includes one or more processors, memory, and support circuits. The one or more processors may include a central processing unit (CPU) and may be one of any form of a general purpose processor that can be used in an industrial setting. The memory, or non-transitory computer-readable medium, is accessible by the one or more processors and may be one or more of memory such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. The support circuits are coupled to the one or more processors and may include cache, clock circuits, input/output subsystems, power supplies, and the like. The various methods disclosed herein may generally be implemented under the control of the one or more processors by the one or more processors executing computer instruction code stored in the memory as, for example, a software routine. When the computer instruction code is executed by the one or more processors, the one or more processors controls the CMP systemA to perform processes in accordance with the various methods disclosed herein.

illustrates a schematic top view of a CMP systemB and is configured similar to CMP systemA, except as otherwise described. As shown in, the polishing stationsmay be placed in a circular arrangement. In such a configuration, the non-contact cleaning unitand the contact cleaning unitsare disposed between the polishing stationssuch that the contact cleaning unitsis in the pass-through between adjacent polishing stations. The non-contact cleaning unitsare adjacent to the at least one carrier headof each of the polishing stations, such that the substrate undergoes a non-contact cleaning immediately before being polished in the. Having the contact cleaning unitsin the pass-through between polishing stationsminimizes polishing-station-to-brush-clean transfer time, reducing defects in the substrate, and reduces the need for additional contact cleaning units in the cleaning moduleresulting in a reduced overall footprint of the entire tool. Alternatively, the CMP systemB may only have the contact cleaning units.

is an isometric view of a contact cleaning unit, e.g., brush cleaner, which may be utilized in the CMP systemas described above. A lid portion of the brush cleaner, which includes a door, has been removed fromfor ease of discussion. The brush cleanershown incan be a scrubber type brush box-type horizontal cleaner. The example brush cleanerincludes a tankthat is supported by a first supportand a second support. The brush cleanerincludes a cylindrical rollercoupled to an actuator (not shown) located inside the tank(shown in).

In operation, the first and second supports,may be moved simultaneously relative to a base. Such movement may cause the first and second cylindrical rollersto close against the substrateas shown in, or to cause the first and second cylindrical rollersto be spaced apart to allow insertion and/or removal of the substratefrom the brush cleaner.

is a top view of the brush cleanerinshowing the cylindrical rollersin a processing position where the cylindrical rollersare closed or pressed against major surfaces of the substrate. The brush cleaneralso includes a rotational device. The rotational deviceincludes a roller, which is disposed at the end of an output shaft of the rotational deviceand is configured to support and/or engage the substrateand facilitate rotation of the substrateabout an axis that is perpendicular to the horizontal plane (i.e., X-Y plane).

During processing in the brush cleaner, the cylindrical rollersare brought into contact with a substrate while they are rotated, and while the substrateis rotated by use of the supporting rollersthat are coupled to the output shafts of the rotational device. A second processing fluid, such as deionized (DI) water and/or one or more second substrate cleaning fluids (e.g., acid or base containing aqueous solution), is applied to the surface of the substratefrom a second fluid source while the substrateand cylindrical rollersare rotated by the various actuators and motors.

is an isometric view of one or more embodiments of a scrubbing devicedisposed within the brush cleaner. The scrubbing deviceshown inis depicted with a substrateloaded therein, such that the scrubbing deviceis in a loaded state. The scrubbing deviceincludes a pair of cylindrical rollers. Each brush includes a set of multiple raised nodulesacross the surface of the brush, and a set of multiple valleyslocated among the nodules. The pair of cylindrical rollersare supported by a pivotal mounting adapted to move the cylindrical rollersinto and out of contact with the substrate(e.g., a semiconductor wafer) supported by a substrate support (which may also be referred to as a wafer support), thus allowing the cylindrical rollersto move between closed and open positions so as to allow a substrateto be extracted from and inserted therebetween as described below.

The scrubbing devicealso includes a substrate support adapted to support and further adapted to rotate a substrate. In one aspect, the substrate support may include a plurality of rollers(one shown) each having a groove adapted to support the substratevertically.

The scrubbing devicemay further include sprayerscoupled to a sourceof cleaning fluid via a supply pipe. The sprayersare configured to dispense a high-pressure liquid spray onto the substrate surfaces, aiding in the removal of particles, contaminants, and residues. The sprayerscan incorporate various configurations, such as a fluid jet, spray bar with nozzles, shower-style spray manifold, or cryogenic aerosol jet.

In various embodiments of the present disclosure, the cleaning fluid utilized in the brush cleaner may include, but is not limited to deionized (DI) water, diluted citric acid, diluted Quaternary ammonium compound (a mixture of organic solvents, such as glycol ether, tetramethyl ammonium hydroxide, and other additives), diluted ammonium hydroxide (NHOH), diluted hydrogen peroxide (HO), NHOH and HOmixture (SC1), diluted hydrofluoric acid, sulfuric acid (HSO) and hydrogen peroxide (HO) mixture (SPM), Electra clean, or any other liquid solution used for substrate cleaning.

In one or more embodiments, the sprayersmay be positioned to spray a cleaning fluid at the surfaces of the substrateor at the one or more scrubber brushes during a scrubbing process. In one or more embodiments, substrate cleaning fluid and/or brush cleaning fluid may be supplied from an internal region of the scrubber brushes (e.g., cylindrical rollers) themselves. Fluids provided to the interior of the scrubber brushes passes through pores to clean the surface of the substrate or remove debris found on the surface of the scrubber brushes.

illustrates a flow diagram of a methodof polishing a substrate, e.g., substrate, which may be performed by a controller of a CMP system, e.g., controllerof CMP systemA. In operation, the substrateis placed on the non-contact cleaning unitby a robot arm (not shown). The non-contact cleaning unitthen cleans the substratein operationusing a non-contact cleaning method, such as megasonic cleaning or spray cleaning. For example, the substratemay undergo spray cleaning where theuses high-pressure jets of cleaning solution directed toward the substrateto dislodge particles and contaminants.

Once cleaned, the substrateis transferred, e.g., by the transfer station, to one of the at least one carrier headof a first polishing station of the polishing stationsfor polishing in operation.

In operation, the substrateis transferred from the first polishing station to a contact cleaning unit. The contact cleaning unitthen cleans the substratein operationusing a contact cleaning method, such as brush scrubbing, to clean the substrate. For example, the contact cleaning unitmay be a horizontal brush cleaner, e.g., brush cleaner, which is adapted to rotate cylindrical rollersthat are pressed against major surfaces of the substrate. The cylindrical rollersmay the substrate as a processing fluid is applied to the surface of the substratefrom a fluid source as the cylindrical rollersare rotated. Alternatively, the methodmay exclude operation, such that the substrateis transferred directly to the first polishing station of the polishing stationsbefore cleaning in the contact cleaning unit.

Once the substrateis cleaned in the contact cleaning unit, the substrateis transferred to a second polishing station of the polishing stationsfor additional polishing during operation. In optional operation, the substratemay undergo a second non-contact cleaning process in a second non-contact cleaning unit after polishing in the second polishing station before being transferred to the cleaning module. Contact cleaning the substrate, such as by a contact cleaning unitdisposed in the pass-through between polishing stations, minimizes polishing-station-to-brush-clean transfer time, reducing defects in the substrate.

When introducing elements of the present disclosure or exemplary aspects or embodiments thereof, the articles “a,” “an,” “the” and “said” are intended to mean that there are one or more of the elements.

The terms “comprising,” “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

The term “coupled” is used herein to refer to the direct or indirect coupling between two objects. For example, if object A physically touches object B and object B touches object C, the objects A and C may still be considered coupled to one another-even if objects A and C do not directly physically touch each other. For instance, a first object may be coupled to a second object even though the first object is never directly in physical contact with the second object.

While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.